In recent years, in mobile communication, there has been a demand for efficient communication in both space and time from the viewpoint of dealing with different communication capacities between uplinks and downlinks, that is, so-called non-symmetrical channels, the simplification of hardware at the mobile station side, and the improvement of the efficiency of utilization of the frequency. Particularly, in view of the adoption of W-CDMA (wide band code division multiple access) as a wireless access scheme for the next generation mobile communication system IMT2000, transmission diversity using a plurality of antenna elements, adaptive antenna arrays using a plurality of antenna elements, and other systems have been proposed as powerful technologies for increasing the capacities of the W-CDMA system.
However, in the prior art described above, there has been almost no study relating to the correlation of the transmission signals due to the interference among beams in the case of transmission by a plurality of transmission beam at the transmitting side. Further, the correlation of the transmission signals due to the interference among beams has not been utilized actively to improve the communication efficiency and to improve the quality of communication. Thus, in the case of transmitting and receiving signals by forming a plurality of beams, that is, so-called space diversity, the interference among beams has almost always been suppressed as much as possible to suppress interference and the correlation of transmission signals has not been utilized effectively.